Add a bus driver for bitbanging a 1-Wire bus over a GPIO.
Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
---
drivers/w1/Kconfig | 6 ++-
drivers/w1/Makefile | 1 +-
drivers/w1/w1-gpio.c | 160 ++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 167 insertions(+), 0 deletions(-)
create mode 100644 drivers/w1/w1-gpio.c
diff --git a/drivers/w1/Kconfig b/drivers/w1/Kconfig
index 0c056b4c06a9..ccc3ae15db86 100644
--- a/drivers/w1/Kconfig
+++ b/drivers/w1/Kconfig
@@ -12,6 +12,12 @@ config W1
if W1
+config W1_GPIO
+ bool "Enable 1-Wire GPIO bitbanging"
+ depends on DM_GPIO
+ help
+ Emulate a 1-Wire bus using a GPIO.
+
endif
endmenu
diff --git a/drivers/w1/Makefile b/drivers/w1/Makefile
index 26820fa209e1..7fd8697f8419 100644
--- a/drivers/w1/Makefile
+++ b/drivers/w1/Makefile
@@ -1,2 +1,3 @@
obj-$(CONFIG_W1) += w1-uclass.o
+obj-$(CONFIG_W1_GPIO) += w1-gpio.o
diff --git a/drivers/w1/w1-gpio.c b/drivers/w1/w1-gpio.c
new file mode 100644
index 000000000000..091849162533
--- /dev/null
+++ b/drivers/w1/w1-gpio.c
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2015 Free Electrons
+ * Copyright (c) 2015 NextThing Co
+ *
+ * Maxime Ripard <maxime.rip...@free-electrons.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <w1.h>
+
+#include <asm/gpio.h>
+
+
+#define W1_TIMING_A 6
+#define W1_TIMING_B 64
+#define W1_TIMING_C 60
+#define W1_TIMING_D 10
+#define W1_TIMING_E 9
+#define W1_TIMING_F 55
+#define W1_TIMING_G 0
+#define W1_TIMING_H 480
+#define W1_TIMING_I 70
+#define W1_TIMING_J 410
+
+struct w1_gpio_pdata {
+ struct gpio_desc gpio;
+ u64 search_id;
+};
+
+static bool w1_gpio_read_bit(struct udevice *dev)
+{
+ struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
+ int val;
+
+ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT);
+ udelay(W1_TIMING_A);
+
+ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN);
+ udelay(W1_TIMING_E);
+
+ val = dm_gpio_get_value(&pdata->gpio);
+ udelay(W1_TIMING_F);
+
+ return val;
+}
+
+static u8 w1_gpio_read_byte(struct udevice *dev)
+{
+ int i;
+ u8 ret = 0;
+
+ for (i = 0; i < 8; ++i)
+ ret |= (w1_gpio_read_bit(dev) ? 1 : 0) << i;
+
+ return ret;
+}
+
+static void w1_gpio_write_bit(struct udevice *dev, bool bit)
+{
+ struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
+
+ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT);
+
+ bit ? udelay(W1_TIMING_A) : udelay(W1_TIMING_C);
+
+ dm_gpio_set_value(&pdata->gpio, 1);
+
+ bit ? udelay(W1_TIMING_B) : udelay(W1_TIMING_D);
+}
+
+static void w1_gpio_write_byte(struct udevice *dev, u8 byte)
+{
+ int i;
+
+ for (i = 0; i < 8; ++i)
+ w1_gpio_write_bit(dev, (byte >> i) & 0x1);
+}
+
+static bool w1_gpio_reset(struct udevice *dev)
+{
+ struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
+ int val;
+
+ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
+ udelay(W1_TIMING_G);
+
+ dm_gpio_set_value(&pdata->gpio, 0);
+ udelay(W1_TIMING_H);
+
+ dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN);
+ udelay(W1_TIMING_I);
+
+ val = dm_gpio_get_value(&pdata->gpio);
+ udelay(W1_TIMING_J);
+
+ return val;
+}
+
+static u8 w1_gpio_triplet(struct udevice *dev, bool bdir)
+{
+ u8 id_bit = w1_gpio_read_bit(dev);
+ u8 comp_bit = w1_gpio_read_bit(dev);
+ u8 retval;
+
+ if (id_bit && comp_bit)
+ return 0x03; /* error */
+
+ if (!id_bit && !comp_bit) {
+ /* Both bits are valid, take the direction given */
+ retval = bdir ? 0x04 : 0;
+ } else {
+ /* Only one bit is valid, take that direction */
+ bdir = id_bit;
+ retval = id_bit ? 0x05 : 0x02;
+ }
+
+ w1_gpio_write_bit(dev, bdir);
+ return retval;
+}
+
+
+static const struct w1_ops w1_gpio_ops = {
+ .read_byte = w1_gpio_read_byte,
+ .reset = w1_gpio_reset,
+ .triplet = w1_gpio_triplet,
+ .write_byte = w1_gpio_write_byte,
+};
+
+static int w1_gpio_ofdata_to_platdata(struct udevice *dev)
+{
+ struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
+ int ret;
+
+ ret = gpio_request_by_name(dev, "gpios", 0, &pdata->gpio, 0);
+ if (ret < 0)
+ goto error;
+
+ return 0;
+
+error:
+ printf("Error claiming GPIO %d\n", ret);
+ return ret;
+};
+
+static const struct udevice_id w1_gpio_id[] = {
+ { "w1-gpio", 0 },
+ { },
+};
+
+U_BOOT_DRIVER(w1_gpio_drv) = {
+ .id = UCLASS_W1,
+ .name = "w1_gpio_drv",
+ .of_match = w1_gpio_id,
+ .ofdata_to_platdata = w1_gpio_ofdata_to_platdata,
+ .ops = &w1_gpio_ops,
+ .platdata_auto_alloc_size = sizeof(struct w1_gpio_pdata),
+};
--
git-series 0.8.11
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